Sunday, February 23, 2014

Resonessence Labs Herus


Thanks to the popularity of head-fi, there has been a proliferation of portable products on the market, such as USB powered DACs, combined DAC / headamps and the like.

Head-fi does have a lot of advantages over conventional setups. The overall cost of ownership is more affordable - spending two or three thousand dollars could get you close to cutting edge performance. Further, head-fi is perfect for rigs in land scarce Singapore.

Resonessence Labs was founded by Mark Mallinson, former operations director for ESS Technology. His team members include former ESS employees with intimate knowledge of DAC and ADC design. It would be sensible to assume that these guys know more than a trick or two in handling ESS DACs.


The Herus is a tiny USB powered DAC / headamp based on the ESS 9010-2M chip. Measuring just 6.35 cm long, 3.17 cm wide and 1.9 cm high, it could slip easily into a laptop case for your long and lonely business trips.

A USB Type B socket is located on one end, while the opposite end has a 1/4 inch headphone jack. The Resonessence Lab's logo is placed on the top surface, and glows blue to indicate that power is being received. The logo flashes red prior to lock, and again when there is a sampling rate change.

Build quality is excellent - the Herus is machined from solid aluminum. The base of the unit sports a rather clever thin rubber rectangle to prevent the Herus from sliding off, or marring the surface it rests on.

There are no physical volume controls anywhere on the Herus - this is directly set on your computer instead.

Needless to say, the USB 2.0 connection is asynchronous. Data of up to 32 bits and all common sampling rates  up to 352.8 kHz are supported. DSD 64 and 128, as well as DXD are supported.

Maximum output level is 2.4 V RMS and output impedance is 0.2 ohms. The Herus can sink 126 mW of power into 32 ohms, 95 mW into 60 ohms, 19 mW into 300 ohms and 9.5 mW into 600 ohms.

The Herus is also capable of driving power amps directly, although you will need a customised cable, or 1/4 inch plug to stereo RCA female socket adapter to use your normal RCA interconnects.

Based on it's rated output, the Herus should be able to drive most headphones and IEMs on the market. However, orthodynamic users will need to look elsewhere as the power output is unlikely to be ideal.


Setting up the Herus was easy and glitch-free. PC users will need to download USB 2.0 drivers (written by Thesycon) from Resonessence's website. Mac users can skip driver installation and use the Herus out of the box. I tried installing the Herus on both my PC Desktop and my Macbook Pro. Both installations were fuss-free. The Macbook refused to play DSD, but this was due to a specific software issue on that machine. DSD played fine on a Mac Mini that was running Pure Music, J River Media Centre and Audirvana.

Resonessence's website also warns that the Herus may reset to maximum volume if you move it from one USB port to another. I tried this on my PC, and indeed this was the case. Somehow this had me gingerly checking the volume as I switched between the Coffee and Herus for comparison purposes, although volume settings are maintained as long as you don't swap ports. I was too lily-livered to attempt to connect the Herus directly to a power amp, as an accidental reset of volume could prove disastrous.

Sound Quality

The Herus is a very nice sounding DAC / headamp. It did not take much comparison with the Calyx Coffee sitting on my desktop to realise that the Herus was better in every way.

Compared to the rich creaminess of the Coffee (definitely au lait!), the Herus is clear and crisp sounding. I tried the Herus with a Shure SRH-840, Beyer DT-880 (250 ohm version) and an Audeze LCD 2 Rev 1. The Shure is easy to drive, while the Beyer can probably be said to be middle of the road. The Audeze is more difficult to drive (although considered to be easy to drive by orthodynamic headphone standards) , and the Herus was able to drive the Audeze to far louder levels than the Coffee.

The Herus was most comfortable with the Shure and Beyer. I half-expected the Beyer and Herus combo to be bright enough to make my teeth to fall out, but that somehow did not happen. The Audeze lacked the same effortless quality when matched with my Schitt Lyr (no surprise there given the power limitations of the Herus), so keep the pairing to more modest loads.

Bass is very tight and impactful with the Herus. It punches lower, harder and faster than the Coffee. Perfect for the listener who believes that music should have visceral impact. The bass is of the drier variety though, and lacks a bit of upper midbass bloom. To use Piano notes as an illustration, left hand notes have all the necessary attack and decay, but could do with a little bit more heft and warmth.

Coming to the midband, the Herus is a lot more open and detailed too, with voices presented with clarity and texture. As a downside, sibilance is more obvious with the Herus. There is a just hint of body here. When listening to Eva Cassidy and Rebecca Pidgeon, both ladies can sound a bit thin and harsh on some equipment. The Herus adds slight weight and tonal density that should make female vocals easy on the ear, and non fatiguing in the long run.

Treble is fast, crisp and clean. Acoustic space and the decay of instruments are rendered very convincingly, with very good retrieval of low level information. Listening to Eva Cassidy's "Live at  Blues Alley", the ambience of the recording venue and the sound from the audience comes across clearly.

I went through my music collection looking for tracks to trip up the Herus, but it handled everything I threw at it with aplomb. Whether it came to gentle chamber works, or gritty rock, the Herus lapped it all up.

How about PCM vs DSD comparisons ? I only had on hand a few sample files I downloaded from 2L and Blue Coast Records. The DSD files had noticeably better attack, decay, and retrieval of low level information. Very promising indeed.


The Herus is a neutral, transparent and dynamic sounding DAC and headamp. I initially found it bright, but this is probably in contrast to the Calyx Coffee which I was using prior to this. I especially appreciated that its openness and detail came without any harshness, which helped keep listener fatigue to the minimum.

It's price tag is not the cheapest, but currently at time of writing, this is the only device that I know of in this price range which is this compact, well-finished and capable of DSD and DXD playback.

I bought the review sample.

Highly recommended.

Price : S$ 450 or US$ 350

Note : A word of thanks to K.M. Poon of Horizon Acoustics Singapore, the Singapore dealer of Resonessence for supplying the review unit.

Tuesday, February 18, 2014

B.M.C. Audio PureDAC

I first heard of Juan Carlos Candeias through his design work with CEC with concepts such as load-effect free (LEF) technology and current injection. I used to own a CEC TL-51XR belt drive CD player which sadly died.

B.M.C. Audio has enjoyed increased visibility locally with the launch of a number of new products over the last year or so. When the PureDAC was announced, there was a certain degree of buzz, with its DSD capability at what was then considered a very affordable price tag. When the product was finally launched some months ago, a number of low cost DSD capable DACs were already in the market, many at a lower price tag than the B.M.C.

Nonetheless, the B.M.C. was intriguing, and I managed to get hold of an almost new unit pre-owned, in a local transaction.

Here are some pictures to whet your appetite. This unit is absolutely stunning in the flesh. Some may find its styling strange - I find it very attractive, and a welcome departure from the usual black box. I unboxed the unit and placed it on a dining table. The girls eyed the unit suspiciously. My wife thought that the central tunnel looked like a telescope. My daughter did not seem impressed. They offered some niceties and went back to doing their own thing. Oh well, I suppose it is a matter of taste.

The two sockets on the right are headphone sockets, one single ended, and the other balanced !

Independent volume control of the preamp section and headphone output is possible

Both balanced and single ended outputs are possible. The RCA sockets are too closely spaced for my liking. My usual Acrolink interconnects could not fit.

The chassis is finished to a high standard and the extruded aluminum chassis is eminently strokeable


This DAC is equipped with almost anything you could ask for - asynchronous USB that supports up to 24 bit / 384 kHz sampling rate, DSD64 and DSD 128 capability, 4 pin XLR balanced headphone outputs as well as a single ended headphone output via a 1/4 inch stereo jack.

The headphone stage is definitely not an afterthought, being able to deliver up to 1.7 W of power into 100 ohms, more than powerful enough to drive most cans on the market, especially the planar magnetic models which are currently popular. However, do note that the current is limited by a protective circuit to 200 ma for safety purposes for low impedance phones. The balanced headphone output is a low impedance design while the single ended headphone output has a higher nominal output impedance of 100 ohms.

Digital inputs include 1 x Toslink, 1 x coaxial (RCA), 1 x USB and 1 x AES/EBU. I personally prefer BNC to RCA, but the latter is far more common in consumer grade hardware. Analog output is available via both RCA and XLR. The coaxial jack on my unit is different from the official pictures on B.M.C.'s website, which show a recessed RCA jack. Bear this in mind when using your cable of choice. Neither an Acrolink D-5000 nor Acrolink A-2080 RCA cable were able to fit the analog output jacks as they were too closely spaced together for the large diameter plugs used by Acrolink.

Note also that the coaxial, Toslink and AES/EBU inputs support a maximum sampling rate of 96kHz.

A slim but rather flimsy plastic remote control is also provided, which allows control of the preamp output, headphone stage, mute for both and choice of input. Switching off the unit resets the volume to a level of 10 (59 is said to be standard output voltage, presumably, 2V). Depending on how you look at it, this is either annoying (you will need to increase the volume back to your usual level), or prudent (just in case you forgot to decrease the volume after use). In any case, it is a lot safer than my Antelope Zodiac Gold that resets to full output when power is cut.

The two grey Toslink sockets are for use only with compatible B.M.C amplifiers or active speakers, which activate D.I.G.M. (Digital Intelligent Gain Management), controlling volume by setting gain directly at the amplifier, instead of using a resistive network. D.I.G.M. is also used in the PureDAC, which allows very high quality volume control. I prefer this to digital volume control which  introduce problems of bit reduction at high attenuation levels. Throw in a power amp, and you are in business if the PureDAC is your only source.

The front central display shows useful information such as the volume setting of both the analog output and headphone stage, as well as sampling rate, and DSD operation.

The Pure DAC is well finished and sturdily built, with a total weight of 5.4 kg.

Sound Quality

The PureDAC was placed in my system rack, where my Calyx Femto DAC usually resides. Power was fed through an Acrolink Mexcel 7N-7500 power cord. Due to the issues with my Acrolink cables, I used a pair of Nordost Frey RCA interconnects instead. USB connection was made via a Wireworld Platinum cable, and my Cary CD-500 was hooked up to the PureDAC's coaxial input via an Oyaide DR-510 cable. The PureDAC benefits greatly from footers, and it sounded substantially better with a trio of Finite Element Ceraballs, which remained in place throughout the review period.

Despite the unit being well run-in, the PureDAC was disappointingly vague and confused in it's first few minutes of operation from cold, before blossoming after about half an hour. Do not audition this DAC from cold ! Left continuously switched on, the PureDAC became slightly warm to the touch.

Once in the mood, the PureDAC puts out a pleasant performance. Bass has good extension and slam although both the Calyx Femto and Antelope Zodiac Gold have more impactful and dynamic bass lines. This is most noticeable on kick-drum lines and the tympani in orchestral works which show restraint in the last degree of extension. I also noticed that the left hand on Piano is less impactful compared to my reference equipment.

The midrange has a slight honeyed glow and density to it, imparting a subtle sweetness and added body to voices. Female vocalists have a mildy chestier tone. There was a tendency to downplay sibilance with a smoothening of subtle vocal inflexions. The trade-off is very slight, and does not detract from the original enjoyment of the PureDAC.

High frequencies are clean, with good rendering of decay and space. However, the Calyx Femto still has the PureDAC licked when it comes to three dimensionality, soundstage depth and high frequency extension. The Femto DAC has the uncanny ability to resolve instrument decay and ambience detail to a level which the PureDAC is unable to reach. Given that the Femto DAC is more than three times the price of the PureDAC, lacks a headphone section, and lacks DSD support, this is quite forgiveable and to a large extent, expected.

Between the USB and coaxial input, the latter is weightier sounding, with a slightly bigger image size and better attack but coarser detail. I would not rate either input as being superior to the other, they just sound different. Out of curiosity, I tried increasing the upsampling of the Cary to 192 kHz (the upsampling applies to the digital output too) . The signal initially locked on fine but proved unreliable in the long run. So, you can take B.M.C.'s claimed sampling rate limitation for the non-USB inputs seriously.

After becoming acclimatised to the PureDAC, it was quite enjoyable. Moving from the Calyx 24/192 to the Femto DAC on the other hand, and backwards again, was devestating. Although I have not had the 24/192 in my system for some time now, I can safely say that the PureDAC outperforms it and offers better value with a richer feature set at a similar price tag.

I tried the headphone section through a pair of Beyer DT-880 250 ohm cans, using the single ended output - B.M.C. was not joking when they said in the manual, "Note : This is not the recommended headphone operation mode for the PureDAC." If you are thinking of buying the PureDAC for single ended headphone duties, one word - don't. Not, unless you are tasking amplification duties to a dedicated headamp. My Beyer sounded flat and veiled compared to being driven by my DIY Pimeta or Schitt Lyr headamps. The seller let me test the PureDAC through his Audeze LCD2.2 using balanced headphone drive - it was quite good ! Inspired, I built a balanced headphone cable for my Audeze. My Audeze LCD 2.1 is darker sounding than the 2.2 and this was not really an ideal partner for the PureDAC. Tonal matching aside, the balanced headphone section had far greater bass control, gutsiness and transparency compared to the single ended output. The PureDAC had enough current and voltage to drive the Audeze to ear splitting levels. The Head-Fi crowd will definitely give a nod to B.M.C. for their efforts here.

The PureDAC worked quite fine as a preamp, connected directly to my Conrad Johnson power amp. In fact it worked more than fine. I also tried hooking the PureDAC directly to a Job 225 solid state power amp. The combination cost less than S$ 5,000 and was doing a wonderful job powering my Focal Diablo Utopia speakers. I did prefer routing the signal through my Conrad Johnson ET3 SE preamp for additional tonal density, bloom and air - but the difference was not as much as I would have expected. This is definitely a god-send for audiophiles on tight budgets.

How does the PureDAC perform on DSD ? Despite a hair tearing evening, I could not get Pure Music (Version 1.89 running on OS/X Mavericks) to co-operate with the PureDAC. Then again, I had no luck either on a Resonessence Herus DAC I had on loan from a dealer. I knew both units had no issues, as the Herus worked fine with DSD on my PC using Foobar, while I listened to the seller's DSD files at his place, using JRMC for PC. Repeated tries just resulted in a solitary click followed by silence.

Strangely, I tried the PureDAC again on another Mac computer running on OS/X Mountain Lion in the house and the same DSD files worked fine on both Pure Music (Version 1.88) and Audirvana Plus (Version 1.5.12). Go figure ! For what it is worth, DSD files downloaded from Blue Coast Records were clearly superior to their PCM counterparts. The sympathetic computer was too far from my main system, and hence I could only do quick comparisons using headphones.


The PureDAC deviates slightly from neutral with a sweet and richer midrange presentation. It has good bass and treble. Soundstaging, imaging and resolution were above average in absolute terms. In context of its asking price, the PureDAC has outstanding performance and it's shortcomings are only obvious when directly compared to the much more expensive equipment I had on hand. Evaluated in isolation, it is immensely likable.

Consider also that the PureDAC is not just a DAC - it is a capable preamp and balanced headphone amp. De-clutter your system by removing two additional boxes, two power cords, two interconnects, and two shelves ! Add a modest price tag (S$ 2,200 in Singapore) to that, and you have an absolute winner.

Sunday, February 2, 2014

Job 225 Power Amp


I've just got a new Job.

A Job 225 that is. After looking at all the positive information on audio forums out there, I placed an order last week. For those unfamiliar with Job Electronics Inc, it is an affiliated company of Goldmund and shares technology used in Goldmund products. Without sounding too condescending and dismissive, you could consider Job products as Goldmund derived products on the cheap for the average man in the street.

The Job 225 can be ordered directly online at I previously failed to secure a unit when the batch sold out and I jumped on the opportunity last month when it was available again. Ordering the Job was a simple process, and 4 days later, the Job was sitting on my living room floor - delivered from Switzerland to Singapore within record time.

What makes the Job 225 compelling ? It is a high quality, powerful, compact and affordable amplifier.


According to Job, the 225 delivers 125 watts per channel into 8 ohms, or 210 watts per channel into 8 ohms measured according to Goldmund's FPP standard (whatever that means). It is a high bandwith design, with a +/- 3db frequency response of 2 Hz to 900 kHz. Input impedance is a moderate 51 kohms which should make matching with passive preamps or tube preamps which usually have high-ish output impedance relatively easy. Full power is obtained at 0.75 volts, which makes the Job a high gain design. Looking at Goldmund's white paper available on its website also suggests that the Job is a high damping factor design.

Physically, the Job 225 is very compact, with dimensions of 36 cm x 24.5 cm x 8.8. cm, and a weight of 7kg.

The Job only has single ended inputs, and a power switch rocker on the front panel. A single yellow pilot light indicates operation. The rear panel is a bit crowded, with a fairly large heatsink dominating most of the rear. I did not like the fact that each RCA socket was directly under its respective channel's binding post.

The Job runs quite warm, and it's heatsinks are quite hot to the touch. The unit seems to reach a stable temperature after about 90 minutes of operation.


Setting up the Job required a bit more care than usual due to it's high gain design. An old passive pre-amp that I happened to have lying around sounded quite good. Based on a 100K Ohm Alps Black Beauty pot, the combination had decent dynamics and drive, without high-frequency roll-off.

Switching out the passive pre-amp for a Conrad Johnson ET-3 SE preamp yielded even better drive and dynamics, but with far too much gain and tube-noise. The ET-3 SE being also a high-gain design was obviously not an ideal match.

Driving the Job directly from the volume control of either a B.M.C. PureDAC or Antelope Zodiac Gold sounded best. It is worth mentioning though that the Antelope had problems of setting ideal volumes. The Antelope adjusts the volume in 4 db steps up to -36 db, and thereafter in 1 db steps. -40 db was too soft, while -36 db was too loud for some tracks. The B.M.C. had no such problems. As life would have it, the Antelope suited my taste better.

Later into the review, I acquired an Amtrans APCG-01S passive controller. This is essentially a discrete resistor 10K Ohm potentiometer, preceded by a Lundahl transformer to provide 6 db of gain. This offered usefully low output impedance and ended up sounding the best of all the preamps on trial here.

Sound Quality

The Job was evaluated after 60 hours of burn-in time.

Initial impressions were quite promising - this is definitely a special amplifier for it's modest price tag. Sweet, and slightly rich, this is an organic and musical amp - not likely to appeal to those who like razor sharp focus and laser-like precision.

Bass is the most striking quality of the Job - very tight grip, coupled with excellent articulation quality and bloom. Bass notes are tuneful, tight and very fast. On this single aspect, the Job is capable of embarrassing much of the competition out there.

Other outstanding qualities are quietness and an absolute lack of grain. The Job has a very black background and very low noise floor. Even with your ear right up against the tweeter, there is almost no hiss.

I have always preferred tube equipment over solid state equivalents. Despite power limitations and more maintenance issues, I have almost always found tube equipment to excel in depth and height perception, freedom from grain and overall liquidity of sound. This is of course a generalization, and I have heard excellent solid state designs (Soulution, Vitus and Technical Brain come to mind), and some horrid tube equipment (which shall remain nameless).

The Job has been in my main setup, powering my Focal Diablo Utopia speakers for close to a week, and I must confess to not miss my Conrad Johnson equipment as much as I expected. The Job had an edge over my usual gear in the areas of power and bass control. It avoided the flat paper cut-out effect I've heard from lesser solid state gear and had sufficient image density and size to fool me into forgetting that I was not listening to my tube equipment.

However, I found the Job (paired with a stock power cord and placed directly on my TAOC ASR-4 equipment rack) a bit too mellow and lacking in high frequency extension. After some experimentation, I changed the stock power cord to an Acrolink 7N-4030II terminated with Oyaide P/C-004 plugs. The Job was placed on a set of Franc Audio Ceramic Disc Classic footers. Finally, the stock fuse was changed to a Telos QBT-18. This helped to open up the soundstage and top-end. The rest of the review proceeded with these tweaks in place.

Bass control is an outstanding point for the Job. Tight grip with just the right amount of "wetness" , bloom with great articulation. The bass has good rhythm and you could listen to this amp for hours on end just for this.

In the midrange, the Job presents the human voice with a warm and smooth tone. There is a slightly laidback feel to this, which suits slow and sultry pieces.

On the top end, the Job struck a fine balance between sparkle and warmth. I find some amplifiers too etched and dry in that regard, while others too dark and shut-in.

Resolving power is quite good, and aided by its low noise floor, fine detail is easily discernible, even at low listening levels.

I also tried the Job with my KEF LS50 and Thiel CS 2.7. The KEFs in particular were a good match. Although the Thiels sounded fine, I found the Job to be not as effortless as compared to my 500 watt per channel Virtue Audio ICEBlock M5001 amplifiers. I would stick with easier loads with the Job.

Well after I wrote most of this review, I continued to try the Job with other aftermarket powercords including the Crystalpower Ultra Reference and the Siltech SPX-800. The Job is actually very sensitive to power cords. Both the Crystal and Siltech elevated the Job to very serious equipment territory, with a wide open soundstage and clear tone. I do not expect a typical user to use power cords of that level, but it was an interest experience nonetheless.


The Job 225 may be likely overlooked by some audiophiles on the basis of its affordable price tag. This is a pity - the Job 225 is serious design that quite simply sounds better than any other amplifier I have heard in the price range.

Paired with the KEF LS50 and the B.M.C. PureDAC, you end up with a very serious setup that is affordable yet capable of very high performance.

Lunar New Year Greeting

A warm lunar new year greeting goes out to all Chinese visitors to my blog.

Wishing everyone out there a great year of the horse, and may you and your loved ones enjoy good health, prosperity and good fortune.